51568609 has 4 divisors (see below), whose sum is σ = 51731604. Its totient is φ = 51405616.

The previous prime is 51568597. The next prime is 51568619. The reversal of 51568609 is 90686515.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90686515 = 5 ⋅18137303.

It can be written as a sum of positive squares in 2 ways, for example, as 12780625 + 38787984 = 3575^2 + 6228^2 .

It is a cyclic number.

It is not a de Polignac number, because 51568609 - 2⁵ = 51568577 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51568619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81022 + ... + 81655.

It is an arithmetic number, because the mean of its divisors is an integer number (12932901).

Almost surely, 2^51568609 is an apocalyptic number.

It is an amenable number.

51568609 is a deficient number, since it is larger than the sum of its proper divisors (162995).

51568609 is a wasteful number, since it uses less digits than its factorization.

51568609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162994.

The product of its (nonzero) digits is 64800, while the sum is 40.

The square root of 51568609 is about 7181.1286717340. The cubic root of 51568609 is about 372.2160868307.

The spelling of 51568609 in words is "fifty-one million, five hundred sixty-eight thousand, six hundred nine".